How to Do Skull Crushers (Video)

Doing “skull crushers” might not sound particularly good for you, but if you’re looking to add size and strength to your arms, this triceps isolation exercise is a great option.

“The skull crusher is an effective way to work all three heads of your triceps,” says Trevor Thieme, C.S.C.S. “Especially if you use dumbbells, which work each arm independently, identifying any strength imbalances, increasing the instability of the exercise and, thus, muscle recruitment in your arms, shoulders, and core.”

Plus, change up your grip and/or the angle of your bench, and you can emphasize different heads with the skull crusher exercise to build balanced, strong triceps that turn heads.

Here’s a guide on how to do dumbbell skull crushers with perfect form.

Dumbbell Skull Crusher Exercise: Step By Step Instructions

Appears in: Body Beast >> Chest/Tris

Lie down on a bench or the floor holding a pair of dumbbells directly above your chest with your palms facing each other. Your feet should be flat on the floor.
Without moving your upper arms, bend your elbows and slowly lower the weights toward the sides of your head. Avoid flaring your elbows.
Reverse the move to return to the starting position. Repeat for reps.

Bonus Tips for Doing the Skull Crusher

Your upper arms should remain straight and perpendicular to the floor for the duration of each set.
The only parts of your body that should move are your forearms.
Also, speed is not your friend with this exercise. It’s not a power-building move. Lower and lift the weights slowly and under control. Not only will that increase your triceps’ time under tension — a key muscle growth stimulus — but it will also reduce your risk of injury.

How to Make the Skull Crusher Easier

Besides using lighter weights, you can do EZ bar or barbell skull crushers. The bar transfers the work of stabilizing the weight across both arms, allowing you to lift slightly more.

How to Make the Skull Crusher Harder

Increasing the amount of weight is the simplest way to intensify skull crushers, but slowing down the pace of movement will also make the move more challenging.

Variations on the Skull Crusher

Effective variations on the move include changing your grip (e.g., from neutral to overhand), changing the angle of the bench (e.g., from flat to incline or decline), and changing the equipment you use (e.g. an EZ bar, Smith machine, etc.)

Switching up how you perform the exercise can change which head of the triceps is emphasized, enhancing overall muscle development and strength gains.

And if this move proves to be uncomfortable for any reason, you can instead try other triceps exercises, like the overhead triceps extension or triceps kickback.

Benefits of the Skull Crusher

In addition to being a highly effective triceps builder, the skull crusher can be performed with a variety of equipment.

Whether you do a dumbbell skull crusher, barbell skull crusher, or use an EZ bar, go as heavy as you safely can, and you’ll see results.

What Muscles Does the Skull Crusher Work?

Two-thirds of your upper-arm musculature are occupied by your triceps, and the skull crusher is one of the most effective ways to build this muscle group.

All three heads of the triceps (lateral, medial, and long) fuse together and attach to the top of your forearm, with the lateral and medial heads originating at the humerus (upper arm bone) near the shoulder, and the long head originating at the scapula (shoulder blade).

The lateral and long heads are the most visible ones, forming the classic “horseshoe” shape associated with well-developed triceps (long on the inside, lateral on the outside).

The medial head lies under the other two, and while it doesn’t contribute much to the shape of the muscle, it adds substantially to its overall mass.